Plastic engine covers
- Thread starter mclasser
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purely aesthetics.
It traps heat, and heat is an enemy to any plastics including connectors, vinyl-based wiring loom (accordion sleeves), wiring plastic connectors, etc.
Q.
It traps heat, and heat is an enemy to any plastics including connectors, vinyl-based wiring loom (accordion sleeves), wiring plastic connectors, etc.
Q.
Maybe a little sound insulation, but that's it. I removed mine, as it was in the way of my OCD frequent visual inspection of the engine.
Many help with NVH. Some help with airflow.
Why worry? All properly running cars have excess cooling capacity, so any trapped heat would be insignificant. And if your cover is one of those that manages airflow, you might end up with WORSE cooling if you remove it.
Why worry? All properly running cars have excess cooling capacity, so any trapped heat would be insignificant. And if your cover is one of those that manages airflow, you might end up with WORSE cooling if you remove it.
I leave mine on because it covers up the delicate 20 gage fuel injector wires. Leaving those wires uncovered and out in the open makes me nervous. I wish the auto manufacturers would use heavier gage wires if for no other reason than strength and durability.
The covers keep water and debris out of the spark plug wells.
Most modern engines have deeply recessed spark plug wells. This is pretty much unavoidable with a central spark plug surrounded by valves.
I can clean my engines with a hose or pressure washer when the covers are in place with no problem. But with the cover off every drop of water close to the engine seems to end up in the spark plug wells.
Surprisingly the head does not get hot enough dry out the wells by direct boiling, and there isn't enough air flow for the water to evaporate. I wouldn't worry about the covers reducing the lifespan of things underneath. It's a nice even 70-80C, not like the parts exposed to the occasionally intense radiated heat of the exhaust manifold.
Most modern engines have deeply recessed spark plug wells. This is pretty much unavoidable with a central spark plug surrounded by valves.
I can clean my engines with a hose or pressure washer when the covers are in place with no problem. But with the cover off every drop of water close to the engine seems to end up in the spark plug wells.
Surprisingly the head does not get hot enough dry out the wells by direct boiling, and there isn't enough air flow for the water to evaporate. I wouldn't worry about the covers reducing the lifespan of things underneath. It's a nice even 70-80C, not like the parts exposed to the occasionally intense radiated heat of the exhaust manifold.
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my brother noticed a dramatic increase in noise from his hemi when he pulled the cover...put it back, everything was tolerable again.
Automakers generally don't spend a dime on appearance items which can't be seen without opening the hood. The cover is there for reason.
Not all are for looks. Some provide extra noise insulation. My CX7 Mazda used it for ducting cold air to the intake. I took a look at my Mazda CX5 without the cover and instead of a nice aluminum head and cam cover, all I saw was black wires, injectors coil sticking up and stuff. My cover looks nice on. ed
With the move to direct injection more and more cars will have engine covers.
I could see the benefits of sound reduction, and in the winter retaining engine heat. In the summer removing it might help, but as others mentioned the cooling system of the car should be able to handle the heat in the summer. Someone also mentioned keeping junk out of the spark plug tubes. I guess leaving it on is probably the best thing to do.
On forced induction cars with a top mount intercooler, the plastic cover helps force air from the hood scoop through the intercooler. Probably not the typical use, but an example of the functionality of what is usually considered an esthetic part.
Kestas
Staff member
Originally Posted By: HerrStig
Automakers generally don't spend a dime on appearance items which can't be seen without opening the hood. The cover is there for reason.
Not true. I worked for an automaker who had an "underhood appearance group," who made sure nothing looked weird under the hood, and in fact liked to make things look attractive under the hood. They didn't like the blue dye left over for crack detection on the master cylinder, and had to spend extra to deal with it. This was 30 years ago.
Automakers generally don't spend a dime on appearance items which can't be seen without opening the hood. The cover is there for reason.
Not true. I worked for an automaker who had an "underhood appearance group," who made sure nothing looked weird under the hood, and in fact liked to make things look attractive under the hood. They didn't like the blue dye left over for crack detection on the master cylinder, and had to spend extra to deal with it. This was 30 years ago.
Of the cars I have the MB E430 V8 has partial cover over the center of the engine, it is more aesthetics than functional.
Had it on or removed it didn't make any different in sound or engine performance, since it covers only a partial of the middle of the engine it does look better with it on so I leave it on.
For 4-cyl engines the cover is just aesthetics.
Had it on or removed it didn't make any different in sound or engine performance, since it covers only a partial of the middle of the engine it does look better with it on so I leave it on.
For 4-cyl engines the cover is just aesthetics.
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You could use the engine cover off the Pentastar in our minivan as a seat cushion or flotation device is so packed with soft squishy foam. I've had it off for periods of time and didn't notice any difference in NVH. I'm pretty sure that's what it's there for. I could see underhood appearance being more of an importance on certain segments of vehicles, but on a 2013 Dodge minivan? Not so much.
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Originally Posted By: HerrStig
Automakers generally don't spend a dime on appearance items which can't be seen without opening the hood. The cover is there for reason.
Mostly it's dress up, same as fully carpeted trunks, in the old days we were lucky to have a thin rubber mat... Now everything is dressed up, have to keep up with the Jones's toys...
Automakers generally don't spend a dime on appearance items which can't be seen without opening the hood. The cover is there for reason.
Mostly it's dress up, same as fully carpeted trunks, in the old days we were lucky to have a thin rubber mat... Now everything is dressed up, have to keep up with the Jones's toys...
No doubt engine covers appeared when some fool accidentally showed the marketing department where the hood release was.
Clearly they are mostly for appearance, focusing your view to maintenance points and discourage you from tinkering. On our BMW diesel they might also present be to limit noise but I tried it without the covers and there's little difference. The front one provides a half-baked CAI as well.
Clearly they are mostly for appearance, focusing your view to maintenance points and discourage you from tinkering. On our BMW diesel they might also present be to limit noise but I tried it without the covers and there's little difference. The front one provides a half-baked CAI as well.
Kestas
Staff member
Take it off. Put it on the shelf in your garage. Put it back on before you sell your car.
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